Direct current supply system



April 6,1937. J, v, CAPUTQ 2,076,365

' DIRECT CURRENT SUPPLY SYSTEM Filed Sept. 50, 19:55 s Sheets-Sheet 2.38 I ,F 7. J

April 6, 1937.

J. v. CAPUTO 2,076,365

DIRECT CURRENT SUPPLY SYSTEM Filed Sept. 50, 1953 3 Sheets-Sheet 5INVENTOR 15 M x/M Patented Apr. 6, 1937 UNITED STATES PATENT OFFICE2,076,365 DIRECT CURRENT SUPPLY SYSTE James V. Caputo, Girard, OhioApplication September 30, 1933, Serial No. 691,687

8 Claims.

far as I am aware, for supplying direct currents of large magnitude atlow voltage for industrial Processes.

It has been proposed heretofore to utilize commutator-type generators.It has been thought, however, that separate excitation of suchgenerators is essential for successful opera tion.

I have invented a novel apparatus and system for providing a dependablesupply of direct current of large magnitude at low voltage, which ischaracterized by a high efficiency and is thus a marked improvement overapparatus of this sort known heretofore, which was characterized byexcessive losses and correspondingly low efliciency. In accordance withmy invention, Lutilize the principle of the rotary converter but modifythe conventional structure thereof to adapt it to the requirements ofthe special service above mentioned. In order-to supply to the converterthe large alternating currents which are involved in the generation ofhigh-amperage direct currents, without the excessive losses by which theapparatus of the prior art has been characterized, I mount thetransformers supplying the converter on the shaft of the latter forrotation. Only the small alternating currents of high voltage which aresupplied to the primary windings of the transformer, need be conductedthrough sliding connections, such as slip rings and brushes. Thisarrangement is obviously much more efficient than supplying heavyalternating currents from the secondary windings of the transformer tothe converter through such connections. Other features of noveltycharacterizlng my invention will become apparent as the detaileddescription thereof proceeds. v

For a complete understanding of the invention, reference should be hadto the accompanying drawings illustrating a present preferred embodimentand certain modifications thereof. In the drawings:

Figure 1 is a partial section taken on an axial plane through theapparatus of my invention;

Figure 2 is a partial section along the line 11-11 of Figure 1;

commutator 22 of the usual type.

Figure 3 is a partial section along the line III-III of Figure l; I

Figure 4 is a partial section along the line IV-IV of Figure 1;

Figure 5 is a partial section along the line 5 V-V of Figure l;

Figure 6 is a partial .section along the line VI-VI of Figurel;

Figure 7 is a view similar to Figure 1 showing a modified form ofconstruction; 10

Figure 8 is another view similar to Figure 1 showing a further modifiedform of construction;

- and Figure 9 is a circuit diagram illustrating one manner of utilizingthe invention to produce lowvoltage, direct current of large magnitudefrom a high-voltage, alternating current source.

Referring now in detail to the drawings and, for the present, to Figures1 through 6, a shaft I0 is mounted in bearings II. A spider l2 keyed tothe shaft ill provides a mounting for a plurality of transformers I3.The primary windings formers. The transformers are enclosed in housingsl6 and vanes I! mounted thereon induce a flow of current through thehousings.

A spider i8 is also keyed to the shaft I0. Conducting rings l9 aremounted on the spider l8 in spaced relation, and are insulated from eachother and the spider. The secondary windings of the transformers B haveterminals 20 extending axially through certain of the rings is andinsulated therefrom, the terminals of the two ends of each secondarywinding being in electrical conducting engagement with two adjacentrings of opposite polarity.

A spider 2| keyed to the shaft l0 carries a Connectors 23 extend axiallyfrom the commutator bars. Risers 24 are secured to the connectors andhave terminals 25 attached thereto similar to those shown at 20. Likethe terminals 20, the termi- 45 nails 25 extend through certain of therings I! in insulated relation thereto and are electrically connected toone of the rings.

A yoke 26 keyed to the shaft carries a drum armature having a core 21and coils 28 embedded 50 therein. The coils 28 are connected to thecommutator bars through usual risers II. A magnetic yoke 3| having mainpoles 32 and interpoles 33 surrounds the armature. The main poles havemain shunt windings 34, compound 55 shunt windings :35, and compoundseries windings 35. A squirrel-cage winding 31 is embedded in the facesof the main poles 32.

A brush-holder ring 38 is adjustably secured to the side of the yoke 3|adjacent the commutator 22. Brush holders 39 are secured to butinsulated from the ring 38. Each brush holder 39 carries a plurality ofbrushes 40 engaging the commutator 22. Equalizer rings 4| extend aroundthe machine within the ring 38. Brush holders 39 of alternating polarityare in electrically conducting engagement with the equalizer rings ofcorresponding polarity. Connections 42 extend from the equalizer ringsto the series windings 36 and thence to an additional pair of equalizerrings 43 on the opposite side of the machine. The equalizer rings 43 areattached to but insulated from a supporting ring 44 similar to thebrush-holder ring 38. The supporting ring 44 carries a terminal housing45. Connections 46 extend axially and radially from the equalizer rings43 to a plurality of terminal leads 4'! extending around the shaft I0within the housing 45, secured thereto by bolts 48 but spaced therefromby insulation 49. Successive connections 46 around the circumference ofthe machine are secured to terminal conductors 41 spaced at increasingdistances from the armature of the machine, adjacent leads 4'! havingopposite polarity. The terminal leads extend radially from the housing45, as shown in Figure 2, in any desired direction to carry the currentto the load.

Figure 7 illustrates a modified form of construction which is similar ingeneral to that of Figures 1 through 6. Corresponding elements thereofare indicated by the same reference numerals with a prime affixedthereto. The difference between the embodiments of the inventionillustrated in Figures 1 and 7 is that in the latter, the transformers13 are mounted on the opposite side of the machine from the cormnutator.The risers 24' are, therefore, connected to the ends of the armaturecoils 28 on the opposite side from the commutator instead of to the'commutator itself. The construction of the machine of Figure '7 is,however, otherwise practically the same as that of Figure 1.

Figure 8 shows a further modification which is 50 only slightlydifferent from that of Figure 7. In Figure 8, the transformers l3 arepositioned within the spider 26 instead of in axially spaced relationthereto. Obviously, this construction is very compact. Except for theabove-mentioned difference, it is substantially the same as theconstruction of Figure '7.

Figure 9 illustrates a schematic diagram of connections for a typicalinstallation of the invention. High-voltage. alternating current is 60supplied to the brushes and slip rings I4 from transformers connected inopen delta, through a switch 56, to a supply circuit 51. Thetransformers 55 are equipped for tap changing under load by switches 58and auto-transformers 59. An induction regulator 60 is connected betweenthe transformers 55 and the slip rings and brushes l4. The combinationof the tap changing transformers and the induction regulator permits anydesired voltage to be applied to the 70 slip rings. This permits thesupply of direct current at any desired voltage within a wide range.

The excitation for the main shunt field winding 34 may conveniently beobtained from a rectifier 6|, which is supplied by a transformer 62 con-75 nected across the transformers 5.- Th? exc g current traversing thewinding 34 may be controlled by a carbon-pile rheostat 63 operated by arelay 34 in series with the direct current load circuit. The relay 34,furthermore, by means of a rack and pinion 64, a shaft 65 and gearing66, controls the adjustment of the induction regulator 60 to maintain aconstant voltage and current on the direct current side. The serieswinding 36, of course, is connected in series with the relay 34 and theterminal leads 41.

The shunt compound winding 35 is energized by the output of a rectifier61, which is connected across a transformer 68. The transformer 68 issupplied by current transformers 69 in the main connections between thesupply circuit and the induction regulator 60. The energization of thefield winding 35 is thus proportional to the current supplied to theconverter.

It will be apparent from the foregoing description that the invention ischaracterized by numerous advantages over the systems and apparatus ofthe prior art for supplying direct current of large magnitude at lowvoltage. In the first place, the system permits a very nice control ofthe direct-current voltage. The maintenance of a constant,direct-current voltage, or even a voltage which increases with load, ifdesired. is insured by the compound excitation and the automatic controlof the main shunt field. The losses incident to the transmission of thelarge. alternating currents necessary to supply energy to the converterare materially reduced by placing the transformers on the shaft of theconverter and connecting the transformer secondaries to the converterarmature by short connections which are interleaved so as to reducereactance. The interleaving of the inductors reduces the socalledalternating-current resistance thereof to approximately the value of thedirect-current resistance. In other words, the non-uniform distributionof the current resulting from skin effect is minimized. At the sametime, the construction of the converter is characterized by all thedesirable features known to modern engineering practice. A machine ofthe type shown can successfully be operated with self-excitation. Thedisposition of the terminal leads on the opposite side of the machinefrom the commutator is an advantage in that it simplifies constructionand makes possible a design which is symmetrical electrically andmechanically.

Although I have illustrated herein but a few modifications of theinvention, it will be obvious that numerous changes in the system andapparatus described and illustrated may be made without departing fromthe spirit of the invention or the scope of the appended claims.

I claim:

1. The combination with a rotary converter having a field winding andbeing adapted for connection to an alternating-current supply source, ofa source of excitation for said winding comprising a series transformerconnected between the converter and said supply source, and a rectifierenergized by said transformer and supplying its output to said winding.

2. In a rotary converter, a stationary yoke, a shaft coaxial therewith,an armature mounted on the shaft for rotation within said yoke, acommutator on said shaft, a transformer mounted on said shaft forrotation with said armature and commutator, and connections between saidtrans former and armature including a plurality of flat discs disposededgewise on the shaft and rotating therewith, and connections from therings to the transformer windings and to said commutator, saidconnections including terminals extending axially through said discs,insulated from some ,of them and in conducting engagement with at leastone of them.

' 3. Apparatus as set forth in claim 2 characterized by the fact thatsuch connections also include pairs of equalizer rings extending aroundthe yoke on opposite sides thereof.

4. A dynamo-electric machine comprising a yoke, a shaft coaxialtherewith, an armature disposed on the shaft for rotation within theyoke, a plurality of transformers on the shaft, and a plurality of flat,annular interconnecting rings disposed edgewise on the shaft, thesecondary windings of the transformers being connected to the rings, andthe rings being connected to the armature by means including terminalsextending axially through the rings.

yoke, a shaft coaxial therewith, an armature disposed on the shaft forrotation within the yoke, a plurality of transformers on the shaft, 0.commutator on the shaft connected with the armature, said transformersand commutator being both disposed on the same side of said yoke,

connections from said transformers to said commutator on the shaftconnected with the armature, said transformers and commutator being bothdisposed on the same side of said yoke, connections from saidtransformers to said commutator, and terminal conductors extendingcircumferentially of said shaft on the opposite side of the yoke fromthe transformers and having connections extending axially through saidyoke to said commutator.

8. An electric generator adapted to generate a heavy current at lowvoltage comprising a yoke, a

rotor mounted for rotation therein, means for collecting and deliveringthe current induced in said rotor including a plurality of brush holdersspaced radially from and circumferentially about the axis of the rotor,and carrying brushes cooperatingwith conducting means mounted on androtating witlrthe rotor, an individual load lead in conducting relationwith each of said holders, said leads extending axially of said yoke ininductive relation therewith thereby compensating the effect on the yokeof the current induced in said rotor uniformly about the circumferenceof the yoke, said leads extending then radially and c'ircumferentiallyof the yoke substantially to a common point, and thence radially of theyoke.

JAMES V. CAPUTO.

